The commanding officer of one of Canada's Coast Guard icebreakers is dead after an Arctic helicopter crash in frigid northern waters that claimed three lives.

Marc Thibault, captain of the CCGS Amundsen, was killed along with pilot Daniel Dubé and scientist Klaus Hochheim Monday night after their helicopter plunged into the McClure Strait off Banks Island in the western Arctic.

They had been scouting the sea ice to determine the best route for the Amundsen, a research vessel carrying scientists taking myriad measurements of the Northern environment. The expedition was in the most remote part of the Arctic, more than 600 kilometres away from Resolute, Nunavut, where Canada maintains a logistics base for research in the region.

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The tragedy that has hit Canada's premier research platform in the Arctic underlines the risks of operating in such an unforgiving environment.

The crash occurred about 8 p.m. (ET) Monday and Coast Guard staff say the weather was clear with good visibility at the time.

The Amundsen, which had been following the helicopter, reached the crash site later that evening and retrieved three bodies from the 420-metre-deep water, but did not find the chopper. The Coast Guard would not discuss theories on why the aircraft crashed, and the federal Transportation Safety Board is now investigating.

The accident brings the death toll for Coast Guard employees to 13 in the last quarter century. But Mario Pelletier, assistant commissioner of the Canadian Coast Guard for the central and Arctic region, said to lose so many people at once is "very rare."

He said the loss has hit the expedition hard because people live in close quarters, like a family. The Amundsen is heading to Resolute so authorities can decide whether to cancel the mission. The ship was not due to return to its home port of Quebec City until mid-October.

Michael Byers, an Arctic expert at the University of British Columbia who's travelled on the CCGS Amundsen twice, said the Arctic water is deadly.

"The helicopter pilots are very explicit with their passengers that if they have to do an emergency landing, you must not get wet," Mr. Byers said. "Even in a survival suit … your survival time is limited."

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The expedition, a regular undertaking, gathers data on Arctic conditions drawing on everything from fish to snow, ice and water salinity.

"It's a 360-degree collection exercise. It's the equivalent of Canada's lunar lander and the environment is almost as hostile as the moon," Mr. Byers said. He's a project leader with ArcticNet, the consortium that manages the Amundsen's scientific program.

Mr. Thibault had worked for the Coast Guard for 29 years. Mr. Hochheim, a veteran Arctic scientist affiliated with the University of Manitoba, was a respected climatologist and research associate with the Centre for Earth Observation Science (CEOS). Mr. Hochheim leaves behind a wife and three children. The pilot, Mr. Dubé, had flown a Coast Guard helicopter for 28 years.

Prime Minister Stephen Harper offered condolences Tuesday, calling the accident "a grim reminder of the very real dangers faced on a regular basis by those brave individuals who conduct research and patrol our Arctic – one of the harshest and most challenging climates in the world."

The RCMP will meet the Amundsen as it carries the three bodies to Resolute, and counselling staff will meet the crew and scientists to offer support.

Martin Fortier, executive director of ArcticNet, worked with all three victims many times. Everyone is in shock, he said.

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"Those three people were just great people," Fortier said, his voice cracking. "[My] favourite captain, favourite pilot and Klaus was a great person, too."

Steven Chase has covered federal politics in Ottawa for The Globe since mid-2001, arriving there a few months before 9/11. He previously worked in the paper's Vancouver and Calgary bureaus. Prior to that, he reported on Alberta politics for the Calgary Herald and the Calgary Sun, and on national issues for Alberta Report. More

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